The art of inkjet printing is relatively well developed. Commercial products such as computer printers, graphics plotters, and facsimile machines have been implemented with ink jet technology for producing printed media. Generally, an ink jet image is formed pursuant to precise placement on a print medium of ink drops emitted by an ink drop generating device known as an ink jet printhead. Some known printers make use of an ink container that is separably replaceable from the printhead. When the ink container is exhausted it is removed and replaced with a new ink container. The use of replaceable ink containers that are separate from the printhead allow users to replace the ink container without replacing the printhead. The printhead is then replaced at or near the end of printhead life, and not when the ink container is replaced.
A consideration with ink jet printing systems that employ ink containers that are separate from the printheads is to predict an out of ink condition for an ink container. In such ink jet printing systems, it is important that printing cease when an ink container is nearly empty with a small amount of stranded ink. Otherwise, printhead damage may occur as a result of firing without ink, and/or time is wasted in operating a printer without achieving a complete printed image.
Inkjet cartridges with integrated pressure sensing elements are known in the art, such as described in U.S. Pat. No. 6,435,638, INK BAG FITMENT WITH AN INTEGRATED PRESSURE SENSOR FOR LOW INK DETECTION. A purpose of the pressure sensing element is to measure changes in the pressure of the ink or fluid being delivered to the printhead over the ink cartridge lifetime, to provide data for indicating ink level and out-of-ink information.
A challenge for ink cartridges with integrated pressure sensors is protecting the sensor from pressure spikes, which commonly occur during manufacturing, shipping or handling, and can occur due to dropping the cartridge.